Separation of oil from bleaching clay



Patented Oct. 13, 1931 UNITED STATES PATENT oFF CE I JOHANN xommn rrarr, or UETZE, KREIS Bunon'on'r; HANOVER; AND ADOLF smwnoxn, or xxnrs sunenonr, HANOVER,"-GERIVIANY;'ASSIGNORS' TO THE; FIRM nnn'rscnn GASOLIN AKTIENGESELLSCHAFT, or Bea rix, GHARLOTTENBURG, enn- IANY SEPARATION or om rnolvr BLEACHING CLAY No Drawing. Application filed. April 3, 1930, Serial No L4 4L422tand in Germany'May 16, 1927'.

Bleaching clay which has been used for refining mineral oil, contains large quantities of oil which require to be recovered. If the oil containing bleaching clay is extracted with organic solvents, such as petrol, benzol, trichlorethylene, only the oil which was mechanically mixed with the bleaching clay is recovered, and not the part of the oil which was adsorbed. In the known treatment of used bleaching clay by boiling with water also, only the mechanically mixedoil is separated. i 1

In order to remove also the adsorbed oil, the surface of the bleaching clay which has an 5 adsorptive efiect must be altered by chemical means. For this purpose the treatment of the oil containing. bleaching clay with aqueous lyes is known. The bleaching powder thereby assumes a vslimy form which is filtered 3 only with great difficulty, and the working up of large quantities of dilute lyes containing slimy clayhas great disadvantages. The

mineral oil is also often obtained in strongly emulsified form so that a separation of this 5 emulsion is still necessary, which operation is diflicult.

Finally, it has already been proposed to free the used oilcontaining bleaching clay from oil by boiling with acidified water. Ac-

0 cording to the literature of the subject this process produced little satisfactory result.

It has now been found that the adsorbed oil also can be entirely recovered from the used bleaching Iclay, if it is heated with dilute and under the pressure arising thereby.

In the working up of oil containing bleaching clay which has been used for refining fat, the removal of .fat has already been effected by heating with water'under pressure, if necessary with the addition of a splitting agent (sulphuric acid). It was however not to be expected that such a processwould also be useful for refining bleaching clay in the mineral oil industry. Mineral oil cannot be split. In the known process the acid reacts with the fat, in the present process it does'not.

The carrying out of the process is extremely simple. The bleaching clay to be freed from oil is heated in a closed pressure vessel aqueous mineral acid above its boiling point 'to be treated with bleaching clay.

the material divides into three well defined layers, at the top, the recoveredoil, in the middle a clear aqueous layer still having an acid reaction, and at. the bottom the bleaching clay completely freed from oil and satu ratedwith. water. Y I

In this methodof carrying out the process the oil held mechanically by the bleaching clay is obtained mixed with the adsorbed part. If -1t is desire'dto obtain the two quant1t1es of oil separate,.the bleaching clay may first be treated with organic solvents in a manner known, and freed fromthe massof solvent by settling -or filtration, and then subjected to the treatment withmineral acid.

Examples 1. 1 kg. of used bleaching clay containing 30% of oil with 1 litre of 30% sulphuric acid is agitated in a closed vessel by blowing in steam so that the mass is heated and the pressure in the vessel rises to 3 atm. After standing for 3 hours the oil separated above is drawn off by means of the pressure in the vessel through a tube inserted to the appro- 1 priate depth.- Then the slime free from oil settled below is passed through a filter press under the pressure in the vessel.

2. 1 kg. of used bleaching clay containing 30% ofoil is thrice extracted each time with I I 1 litre of hot petrol, each time being allowed to settle and the clear petrol solution drawn ofl. By this means about 200 gm. of oil are extracted, which are obtained from the extract as a residue by blowing away the petrol- J with steam. In quality, this oil-corresponds approximately to the original material, which was treated with the/bleaching clay, and may be added to the next charge of oil The settled clay, still containing the adsorbed oil and mechanically adhering petrol, is treated according to'Example 1. Theoil which settles out consists of the mixture of petrol with 1&0

the oil which was adsorbed, and is separated by distillation. As a residue, 100 gm. of

dark coloured oil are obtained which may be used for inferiorpurposes.

hat we claim is: i

1. A process for recovering mineral oil from spent bleaching clay which has been used to refine mineral oil and which contains oil both adsorbed therein and mechanically adherent thereto, which process comprises mixing with the spent clay a dilute aqueoustion, and a lower layer of water-saturated bleaching clay completely freed from oil, and finally withdrawing the mineral oil layer by means of the vapor pressure generated during the heating.

2. Process as in claim 1, characterized in that the bleaching clay is treated with an organic solvent for the mineral oil to recover the oil mechanically adhering to the clay, before the clay is heated with the dilute aqueous solution of mineral acid.

In testimony whereof we have signed our names to this specification.

JOHANN KONRAD PFAFF. ADOLF SIEWEOKE. 

